A double blind, randomized, controlled study of the effect of addition of butorphanol to 0.25% bupivacaine for bilateral ilioinguinal nerve blocks in post-caesarean patients

Background: Ilioinguinal nerve block (IIB) is highly effective in controlling postoperative pain following inguinal herniorrhaphy, orchidopexy and caesarean sections. Butorphanol has been claimed to increase the duration and quality of analgesia in various nerve blocks. This prospective, randomized, double blind study was designed to compare the effect of butorphanol when added to bupivacaine (0.25%) with plainbupivacaine (0.25%) in bilateral IIBs in post-caesarean patients. Methods: This prospective, double blind, randomized, controlled study was conducted at University College of Medical Sciences / GTB Hospital, Delhi, which is a tertiary care healthcare centre, from March 2006 to December 2008. Sixty ASA 1 or 2 patients, scheduled for elective caesarean section via Pfannensteil incision under general anaesthesia , were selected for the study. The patients who had a known allergy to any of the drugs used; or had placenta previa, eclampsia or severe preeclampsia were excluded from the study. The patients were randomly divided into two groups of 30 each; Group A, to receive bilateral IIB with 0.25% bupivacaine (to a volume ot 10 ml on each side), and Group B to receive bilateral IIB with 0.25% bupivacaine plus 1 mg butorphanol. The randomization was done using computer generated random number tables. Ml the patients completed the study. After administering appropriate antacid prophylaxis, routine general anaesthetic technique was used with rapid sequence intubation. At delivery of baby, all patients received oxytocin infusion followed by inj. morphine (0.1 mg/kg) intravenously, just after the last stitch, bilateral IIB was performed using the prefilled syringes with the block solution. Neuromuscular blockade was reversed and inj. diclofenac sodium (1.5 mg/kgi.m.) was selected as a rescue analgesic. Numeric pain scale (marked 0-10) and simple descriptive pain scoring were used for assessment of pain intensity at 1st, 2nd, 3rd and 4th hours postoperatively and then after 24 hours. The time to first rescue analgesic was noted and the study was terminated with that. The adverse effects, if any, were also noted. Results: More than 86% of Group B and 70% of Group A complained of no pain in immediate 4 hours of postoperative period. In Group B, six patients felt no pain even after 4 hours of postoperative period. In Group A, all patients developed pain after 2 hours. Maximum analgesic effect was observed in Group B (18 hours). Conclusion: Bilateral IIB with 0.25% bupivacaine and 2 mg of butorphanol is more effective and safe post-operative analgesic technique in patients undergoing caesarean section.